CIGARETTE SMOKE FILTER SYSTEM

Abstract: A cigarette smoke filter is provided for use in a smoker's accessory for filtering cigarette smoke, the filter comprises: a tubular filter normally of micro-fibres for removing particulate material from cigarette smoke and optionally an outer filter layer of activated carbon material or the like for adsorbing gaseous components from the cigarette smoke. The efficiencies of the tubular filters is such to remove substantially all of the particulate and gaseous components from the cigarette smoke so that the filtered smoke stream can be discharged into the surroundings free of any cigarette smoke smell.

Description: CIGARETTE SMOKE FILTER SYSTEM FIELD OF THE INVENTION This invention relates to a cigarette smoke filter for use in a smoker's accessory for filtering cigarette smoke and more particularly to filters as used in smoker's accessories which remove substantially all of the particulate and gaseous components of cigarette smoke for discharge into the surroundings. BACKGROUND OF THE INVENTION When a cigarette is smoked, visible smoke is produced, by mainstream smoke spillage, exhale smoke and as well sidestream smoke which is generated by the burning cigarette between puffs. Cigarette smoke is considered objectionable by some persons and has led to no-smoking laws of varying degrees of strictness in certain jurisdictions and environments. A number of prior proposals have been made with respect to structures which are designed to minimize or eliminate the formation of visible smoke, when a cigarette is smoked. However, no device disclosed in the art known to the applicants provides for not only the substantial elimination of all the visible smoke but also provides the same smoking taste and quality to the smoker as if smoked in the normal way. Several devices of various degrees of sophistication have been developed to filter sidestream smoke and/or exhale smoke. U.S. Patent 4,052,179 discloses an example of the standard type of ashtray system which draws sidestream smoke through a charcoal filter contained within a fine wire or glass fibre mesh. A deodorant pad may be included on the exhaust side of the system to mask any remaining cigarette smoke odours not removed by the charcoal filter. Another form of sidestream smoke filter is disclosed in U.S. Patent 4,685,477. A cigarette is inserted in the device which is tubular in shape and is open at each end. When the cigarette is inhaled fresh air is drawn in through an air intake. The lit cigarette is positioned inside the tubular filter. As the cigarette continues to burn, the sidestream smoke permeates the surrounding tubular shaped filter. Because the burning cigarette is housed within the filter, the filter material cannot be affected by heat and is not readily ignited by the cigarette ember. During smoking of the cigarette, the enclosed smoke contaminates the cigarette paper and cigarette tobacco resulting in unsatisfactory taste. U.S. Patent 4,200,114 discloses a smoker's mask which may be placed on the smoker's face. The system provides for inhale and exhale cigarette smoke where all sidestream and exhale smoke is filtered through a single filter. A complex arrangement of check valve is provided to ensure that all smoke passes through the filter or is contained within an enlarged smoking chamber. U.S. Patent 4,790,332 discloses a smoker's accessory in which the cigarette is totally housed. Both sidestream and exhaled smoke are filtered by the same filter. The filter usually consists of two layers. An inner filter made of hepa or like material removes particulates from cigarette smoke. The outer layer of the filter is a polyurethane foam or like material impregnated with charcoal for removing odour from the air as it passes from the inside of the device through the filters and into the surroundings. U.S. Patent 4,899,766 describes a smoke catcher which provides for capture of both the sidestream and exhaled smoke. A fan is used in conjunction with filters to draw the sidestream smoke and exhaled smoke through filters before discharge into the surroundings. The filters comprise in series two or more filter elements. The exhaust fan is located downstream of the filter elements. Alternatively, the exhaust fan may be located to exhaust the smoke to the outside without filtration. U.S. Patent 4,993,435 discloses a smoker's accessory which captures sidestream smoke for inhalation by the user and is provided with an exhale filter arrangement. Several serially arranged filter disks are provided. The filter disk may include charcoal and the like or pressed paper material having a suitable porosity for purposes of filtering the exhaled smoke. A filter disk has also been used in a smoker's accessory having a powered fan within the hand-held unit. The sidestream smoke is drawn from the lit cigarette through a filter disk before discharge to the surroundings in the manner shown in U.S. Patent 4,637,407. Considerable efforts have been made in the area of filters as provided on cigarettes to effect a partial filtration to reduce the amount of tar and nicotine inhaled by the smoker. It is appreciated that cigarette filters however are not designed to remove substantially all of the cigarette smoke so that the smoker continues to experience the usual taste and flavour. Cigarette filters for example, which are tubular in nature are designed to filter some of the smoke particles from the smoke stream. U.S. Patent 3,685,523 discloses a tubular type of cigarette tip filter which partially filters the cigarette smoke as it passes from the interior of the tubular filter to the exterior thereof before inhale by the smoker. A similar type of filter is described in U.S. Patent 3,854,384 involving a tubular filter only offset with respect to the central axis of the cigarette. Both filters are designed to be inefficient to allow the various components of cigarette smoke to pass through the filter so that the smoker realizes the desired taste and flavour. Canadian Patent 1,057,924 as issued to the applicant describes a method of producing polymeric fibres of micron size which can be used in cigarette filters. Such micro-fibre has been used in cigarette filters of the type described in applicant's U.S. Patent 3,882,877 and international application WO90/09741. The micro-fibres produced by the method of Canadian Patent 1,057,924 have increased filtration efficiency compared to cigarette filters of the standard cellulose acetate, charcoal and the like. In order to take advantage of the efficiency of those filters a thin cylindrical filter is provided in the filter tip of a cigarette as described in WO90/09741 which provides for uniform tar delivery while smoking the cigarette. None of the devices described in this prior art provides however, in a portable and compact structure, the significant features of substantial elimination of both sidestream and exhale smoke and that the smoker experiences the same degree of smoking taste and quality as when smoking a cigarette normally. In accordance with this invention, a filter is provided which may be adapted for use in filtering cigarette smoke. The filters are intended to be used with devices such as a compact portable smoker's accessory which permits a smoker to smoke a cigarette while at the same time substantially eliminating at least the sidestream smoke and exhaled smoke. Such device may include an enclosure in which the cigarette is located for smoking. The smoker may draw on the cigarette located within the enclosure to smoke the cigarette and also exhales back into the device where the appropriate filters process either the sidestream smoke or the exhaled smoke. A fan may be provided in the enclosure to ensure a powered air flow through the enclosure so as to supply fresh air as required for proper burning of the cigarette and also to decrease the temperature of air surrounding the cigarette, so as to prevent scorching of cigarette paper and prevent drawing of the hot air from the enclosure by the smoker which would result in unsatisfactory taste and flavour to the smoker. In this way, the same degree of smoking taste and quality could be maintained as if the cigarette were smoked normally. Low pressure drop highly-efficient filtration material generally is employed for filtering both sidestream smoke and exhale smoke. Such highly-efficient filtration material generally comprises a mass of micro-fine fibres. Such filtration conveniently is effected in separate compartments or the same compartments within the enclosure, by different filter elements. The filter element or elements may be constructed to permit filtration of cigarette smoke to be effected prior to contact of such smoke with the permanent structural elements of the smoking apparatus, so as to minimize contamination of non-disposable elements of the device by tobacco smoke components. The smoking apparatus is constructed so that at least the tobacco portion of the cigarette is enclosed within the unit during smoking to ensure that all sidestream smoke is filtered by the unit, and also provides for filtration of exhale smoke such that the activity of smoking is not readily apparent to the casual observer. The smoking apparatus may also be constructed or used without providing for the exhale smoke filtration. SUMMARY OF THE INVENTION According to an aspect of the invention, a cigarette smoke filter for use in a smoker's accessory for filtering cigarette smoke derived from sidestream smoke or exhale smoke, the filter comprises: a tubular filter consisting of micro-fibres for removing particulate material from cigarette smoke, the tubular filter having an inlet end for cigarette smoke to enter an inner elongate chamber within the tubular filter, the tubular filter having a closed end opposite the inlet end, the micro-fibres having an average diameter in the range of about 0.5 to about 10 microns and made from a suitable fibre forming composition, the tubular filter being of sufficient radial thickness to remove substantially all particulate components from cigarette smoke passing radially from the inner elongate chamber through said tubular filter, the micro-fibre filter material having a low pressure drop to permit an air stream to flow through the filter with minimal resistance to such flow. According to a further aspect of the invention, a cigarette smoke filter cartridge for use in a smoker's accessory for filtering sidestream smoke emitted from a burning cigarette comprises: a cigarette tube in which a burning cigarette is placed, the cigarette tube being at least as long as a cigarette to be smoked and having a diameter at least 1.5 times the diameter of a cigarette, the cigarette tube being non- porous to sidestream cigarette smoke, a porous low pressure drop tubular filter element at an end of the cigarette tube for removing sidestream smoke, the filter element having an inlet end for sidestream cigarette smoke to enter an inner elongate chamber within the tubular filter, the tubular filter having a closed end opposite die inlet end, means for connecting a first end of the cigarette tube to the inlet end of the filter element whereby sidestream smoke to be filtered flows along the cigarette tube, into the inner chamber, and radially outwardly through the tubular filter element, and a second end of the cigarette tube being open to permit insertion of a lit cigarette into the cigarette tube, the second end of the cigarette tube being adapted to be received by a holder for a lit cigarette. In accordance with another aspect of the invention, a cigarette smoke filter cartridge for use in filtering cigarette smoke exhaled by a cigarette smoker comprises: an inner tubular filter consisting of micro-fibres for removing particulate material from cigarette smoke, said tubular filter having an inlet end for cigarette smoke to enter an inner elongate chamber within the tubular filter, the tubular filter having a closed end opposite the inlet end, the micro-fibres having an average diameter in the range of about 0.5 to about 10 microns and being made from a suitable fibre forming composition, an outer filter shell surrounding the inner filter, the outer filter shell consisting of activated carbon material held by a support matrix which is porous to air flow, the inner tubular filter being of sufficient radial thickness to remove substantially all particulate material from cigarette smoke passing radially from the inner elongate chamber through the tubular filter, the micro-fibre filter material having a low pressure drop to permit an air stream to flow through the filter with minimal resistance to such flow, the activated carbon outer filter shell being of sufficient radial thickness for adsorbing substantially all gaseous components of cigarette smoke from such filtered exhaled cigarette smoke stream, the cartridge having an end portion adjacent the inlet end, the end portion being received by an exhale mouthpiece to facilitate a user exhaling into the filter cartridge, and the inner tubular filter in combination with activated carbon outer filter providing a filtered air stream substantially free of cigarette smoke for discharge into surroundings. BRIEF DESCRIPTION OF THE DRAWINGS Preferred embodiments of the invention are described with respect to the drawings wherein: Figure 1 is a perspective view of a smoker's accessory with sections thereof removed to show die location of filter cartridges which filter sidestream smoke and exhale smoke; Figure 2 is a section through a sidestream filter cartridge; Figure 2A is an enlarged section of porous mesh used on die filter cartridge of Figure 2; Figure 3 is another section dirough the filter cartridge of Figure 2 showing the assembly thereof; Figure 4 is an end view of die filter cartridge of Figure 2; Figure 5 is a section through an exhale cigarette smoke filter cartridge; Figure 6 is an end view of the filter cartridge of Figure 5; Figure 7 is a section dirough a sidestream cigarette smoke filter in accordance widi an alternative embodiment of die invention; Figure 8 is an enlarged view of portions of the sidestream cigarette filter of Figure 7; Figure 9 is a section through an alternative embodiment for a cigarette exhale smoke filter cartridge; and Figure 10 is an enlarged view of an end of the exhale filter cartridge of Figure 9. DEFINITIONS In order to facilitate a description of die various embodiments of die invention, the following definitions are provided for various components and odier aspects as they relate to the invention. Exhale Smoke means cigarette smoke exhaled by a smoker while smoking a cigarette. Gaseous Components means the components of cigarette smoke other than particulate components and which, if present in an air stream, provides a detectable smell of cigarette smoke. Low Pressure Drop means that the material is sufficientiy porous to air flow that a pressure drop across die material is sufficientiy low tiiat the size of the fan, the power therefor and die exhale pressure are of a nature that the smoker's accessory may be hand held. In order to optimize die accessory design, a low pressure drop is preferably less tiian about 10 mm H 2 0. Micro-fibre means a fibre having an average diameter of about 10 microns or less. Minimal resistance to air flow means that the filter material or the like provides a very low pressure drop to air passing dierethrough. Non-Porous means that the material does not permit flow of the designated components through the material. For example, if a material is non-porous to smoke particles tiien smoke particles are prevented from travelling through the material but for example, air could continue to travel through the material. Particulate Components means the components of cigarette smoke which exist in particle form and are usually of a size less than about 1 micron and normally of a size in the range of about 0.1 to about 0.6 microns. Porous means that the material is sufficientiy open with holes, channels or the like to permit air flow therethrough. Sidestream Smoke means cigarette smoke which rises from a lit cigarette. Substantially All, means in respect of removal of smoke particles or gaseous components from cigarette smoke, that there are substantially no visual or gaseous components remaining which can at least be detected by smell. Suitable Micro-Fibre Forming Composition includes any material which can be formed into micro-fibres and when contacted by cigarette smoke, retains its structure and functional characteristics. Tube or Tubular means an elongate hollow article which has a sidewall of any desired cross-sectional shape, such as, circular, rectangular, square, triangular, oval, multisided (5 sides or greater) and the like. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The various filter components in accordance witii several preferred embodiments of the invention have in common the use of a filter element which is tubular in nature. The tubular filter is preferably made up of micro-fibres of a suitable micro-fibre forming composition which includes materials of mineral, metal, polymer or any other elemental material capable of being formed into the micro-fibres. In accordance witii an aspect of this invention, me filter element may be employed in one configuration with the sidestream smoke filter cartridge or in another configuration as a exhale smoke filter cartridge. The sidestream smoke filter cartridge and die exhale smoke filter cartridge may use in a smoker's accessory particularly of the type that employs a fan to draw sidestream cigarette smoke through the filter cartridge and independently handles die exhale smoke in an exhale filter cartridge which may either be part of or separate from the smoker's accessory for filtering sidestream cigarette smoke. A representative smoker's accessory is shown in Figure 1, and is described in applicant's co-pending U.S. application Serial No. filed , me subject matter of which is incorporated herein by reference. The operation of die smoker's accessory may be understood by reference to mat application, however, for purposes of describing the function of die filters in accordance with this invention, a brief description is provided of die smoker's accessory as shown in Figure 1. The smoker's accessory 10 has a central body 12 which supports and houses a fan 14. Attached to me side of die central housing 12 is a sidestream smoke filtering device 14 which has a housing 16 for a sidestream filter cartridge 18. On die otiier side of die central body portion 12 is an exhale filter device 20 having a housing 22 for an exhale filter cartridge 24. The device 20 is optionally attached to die side of die central body portion 12. It is understood tiiat the device for filtering sidestream smoke may be held in one hand and die exhale filtering device 20 may be held in the otiier hand in its own complete housing separate and apart from the sidestream filtering device. The sidestream smoke filter cartridge 18 comprises a cigarette tube 26 in which a lit cigarette 28 may be placed. The lit cigarette may be inserted in the cigarette tube 26 by pushing the lit cigarette through a cigarette holder 32 which has an insert 34 having a bore 36 therein. The lit end of cigarette 26 is inserted dirough die bore 36. Preferably, die cigarette 28 has its filter tip portion 38 projecting exteriorally of the cigarette holder 32 to allow the user to inhale cigarette smoke in the direction of arrow 40. In this manner, the user, when using the smoking accessory 10 has the same sensation when placing the cigarette filter 38 in their mouth as tiiey would have in a normal smoking environment. The cigarette holder 32 is provided witii a plurality of openings 42 through which fresh air is drawn. The fresh air travels in the direction of arrows 44 along cigarette 28 and over die lit ember 46. The fresh air is drawn dirough the opening 42 by die operating fan 14. The sidestream smoke as picked up by die fresh air 44 as it travels through the filter element 48 in die direction of arrows 50 and along interior of die housing 16 in die direction of arrows 52 and into the inlet of die fan 14 in , the direction of arrows 54. Since the smoke has been filtered of particulate components and optionally of die gaseous components, the fan may exhaust the filtered air through its outiet 56 and dirough the grill portion 58 of the housing 20. It is understood tiiat if the exhale filtering component 20 is not attached to the sidestream filtering device, die fan 14 may exhaust smoke through its outiet 56 to die surroundings. If die filter element 48 only filters out the particulate material then a second filter element may be provided which removes the gaseous components. That second filter element, which is preferably of activated carbon, may be provided over die filter cartridge 48, at die grill 58 of die exhale filter component 20 or at the outlet 56 for the fan 14. The exhale filter cartridge 24 has a filter element 60 with a mouth piece 62 attached diereto. The user exhales in the direction of arrow 64 into the mouth piece and die exhaled air travels through the filter in die direction of arrows 64 and tiien to die surrounding 66 by passage dirough die grill 58. The fan 14 may be provided witii an electric motor 68. In view of the portability of the unit die electric motor 68 may be powered by a rechargeable battery pack 70. A suitable switch may be provided on die central unit 12 for turning the fan on and off. Details of me operation of the smoker's accessory in respect its structure, function and operation is described in more detail in applicant's aforementioned U.S. patent application. The filter components for bom die sidestream smoke filter and die exhale smoke filter are tubular and are preferably cylindrical in shape. The filter material is annular in cross-section and extends d e lengtii of the tubular element. The tubular filter element has an elongate chamber into which the smoke is introduced. The purpose of die filter element is to remove substantially all of die particulate material in the cigarette smoke. In view of the compact nature of die filter elements, the filter material is of a highly efficient low pressure drop construction. The tubular filter element is of sufficient cross-section thickness, that is radial direction from die centre of the tubular element, to achieve such particulate component removal from the cigarette smoke as the smoke passes radially from die inner elongate chamber through die tubular filter. Low pressure drop for the material may be determined and measured in a variety of well known techniques such as displacement of measured mm of H 2 0 in a pressure sensing device. Preferably, the filter material has a low pressure drop in the range of about 5 to about 10 mm of H 2 0. An alternate measure of pressure drop is Corseta units. The filters of this invention should have a Corseta rating in the range of about 10,000 Corseta units. The tubular filter component may comprise a single filter material for only removing particulates. The gaseous components of the cigarette smoke can then be removed by die separate adsorptive-type filtering device located across the entire grill portion 58 of the exhale filter cartridge housing or the fan outlet. Alternatively, the adsorptive material for removing gaseous components from me cigarette stream may surround die exterior of die particulate filter material. The adsorption material is tubular in shape and may contact the inner particulate component filter or may have a larger interior diameter and be spaced from said inner filter. Hence, in e cigarette smoke passing through botii filter elements, both die particulate and gaseous components are substantially all removed. In addition, alternative particulate filter material may be provided on die interior of the primary particulate filter material. This innermost material may be coarse in nature to remove tiie larger particulates before removal of the finer particulates by die next adjacent annular shaped particulate filter. In accordance witii an embodiment of die invention, a suitable filter component for use in die sidestream filter and die exhale filter is shown in Figures 2 dirough 6. With reference to Figures 2 and 3 die sidestream smoke filter cartridge 18 comprises a tube 70 of cardboard or similar inexpensive material, within which is located a cigarette for smoking and a closed-end tubular assembly 72 of cigarette smoke filter material attached to die cardboard tube 70 in any convenient manner, such as by cigarette tipping paper 74. The filter material for the filter element 72 preferably includes a highly-efficient low pressure drop smoke filter material 76 which removes substantially all particulate material from sidestream smoke from a burning cigarette located in die filter cartridge 18, so that only substantially invisible gases pass therethrough. As previously noted, such invisible gases; i.e, the gaseous components, may be removed by an activated carbon filter located elsewhere in the smoking accessory. The highly-efficient low pressure drop tobacco smoke filter material 76 preferably comprises micro-fine material. Such fibrous material generally has a uniform diameter along its length ranging from about 0.5 to about 10 microns. The micro-fibre material is particularly useful in capturing smoke particles of about 0.2 microns diameter and greater in size. It is understood, however, tiiat die sidestream filter can provide a suitable filtration function with a filter of coarse fibres such as the cellulose acetate fibres. Extra thickness of the coarse filter material would be required to achieve substantially complete removal of the particulate components. The important aspect of the sidestream filter is the provision of die tubular filter on the end of die cigarette tube where die tube is of a special size as described witii respect to the embodiment of Figure 2. The preferred micro-fine fibre filter material in the filter element 76 may have a thickness of about 0.3 to about 6 mm and a packing weight of about 5 g/m 2 to about 500 g/m 2 for a sheet thickness in the range of about 0.1 mm to 3 about mm. Preferably the packing weight is in the range of about 10 g/m 2 to about 200 g/m 2 and in die most preferred applications may only range from about 10 g/m 2 to about 50 g/m 2 . The filter material 76 may be used witiiout any support or may be supported in any convenient manner in die filter element 72, such as by an inner layer of coarse filter material 78, which effects an initial filtration of die sidestream smoke before die micro-fine fibres are encountered. The outer surface of the micro-fine fibre filter element 76 may be supported by a suitable porous mesh material 79 which may be crimped or bunched up in a manner to form a seal at 80 as shown in more detail in Figure 4. Such seal closes off the distal end 81 of die tubular filter element 76. The porous mesh 79 may be of plastic which has sufficiently fine openings to retain the micro-fibres. Such mesh may be of die type shown in Figure 2A. The openings 81 are defined by criss-crossing plastic fibres 83. The fibres 83 are sufficiently flexible to permit holding die filter micro- fibres in the desired cylindrical shape. The cardboard tube 70 preferably is provided witii a lining 82 of charcoal or the like to adsorb condensates from the cigarette smoke and hence assist in the elimination of odour. The disposable sidestream smoke filter cartridge 18 is intended to be employed for die smoking of one or more cigarettes and tiien to be discarded. The tubular nature of die assembly ensures tiiat sidestream smoke is filtered before encountering any other part of the apparatus so that the structural elements of the apparatus remain substantially free from condensates from the cigarette smoke and die apparatus can be reused with minimal necessity for cleaning. With reference to an alternative embodiment of die invention of Figures 7 to 10, an activated carbon filter is provided around die tubular particulate filter to remove the gaseous components which pass through the inner particulate filter. With that arrangement, cleaning of the unit is essentially eliminated because all cigarette smoke components are captured in the filter element. The exhale filter cartridge 24 of Figures 5 and 6, comprises an elongate assembly 84 of a tobacco smoke filter material, similar to that described above for the filter element 72, preferably including a highly- efficient low pressure drop smoke filter material 86 which removes substantially all particulate material from exhaled smoke, so mat only substantially invisible gaseous cigarette smoke components pass therethrough. A low pressure drop smoke filter material, such as described above for die filter element 76 may be used. To provide support for die filter element 84, mere is provided an inner layer of coarse filter material 88 and an outer porous mesh material 87 like that of Figure 2A, providing a crimped end closure 90 for die exhale smoke filter element 24. The end closure 90 seals off die end of die filter to ensure that smoke exhaled into the exhale filter travels radially dirough the filter. The tobacco smoke filter material 88 also may be used witiiout any support. A replaceable moudi-piece 62 is provided to facilitate exhale of the smoke into the interior of the cartridge 24. A moutii piece holder 94 is joined to die filter structure 84 in any convenient manner, such as by cigarette tipping paper 96. By using such low pressure drop filtration material, there is little resistance to exhale, so that the exhale by the smoker through the filter approximates a normal exhale action. The filtered exhale smoke is discharged dirough die slots 58 in die side wall of die enclosure 20. The construction of die exhale filter cartridge 24 may be of similar dimensions to die sidestream smoke filter cartridge 18. The construction of the mounting element may be of similar design to die mounting element for the sidestream filter. The dimension of the exhale smoke filter cartridge 24 may be sized to fit inside die tube 70 of the sidestream filter element, to facilitate efficient packing of the elements. A second alternative embodiment for me sidestream and exhale filters is shown in Figures 7 through 10. As shown in Figure 7 the sidestream filter cartridge 18 has a tubular filter element 98 witii an end cap 100 which seals the distal end of die filter element. An elongate chamber 102 is provided witiiin die filter element which has an inlet 104. As discussed witii respect to Figure 1, a lit cigarette is placed in die cigarette tube 106. The cigarette tube 106 is connected to the inlet region of the tubular filter at 108. The cigarette tube 106 has an open end 110 to permit insertion of the lit cigarette tiierein. As shown in Figure 7, the cigarette tube is preferably made up of multiple layers 112. The multiple layers may be glued togetiier at the end 110 to provide structural rigidity and tiiereby adapt die end 110 for insertion in an appropriate holder such as die cigarette holder 32 of Figure 1. It is appreciated tiiat the cigarette tube may be of a single thickness of sheet material or of a single thickness of glass, high temperature plastic or metal. As shown in Figure 8, the tubular filter element 98 comprises an inner filter element 114 and an outer filter element 116. The inner filter element 114 is made up of multiple layers of sheet material 118. The sheet material 118 is layered to form a plurality of layers of filter material in the radial direction, as indicted by arrow 120. The sheet material may be formed of the micro-fibre material described in respect of die high efficiency low pressure drop filter 76 of Figure 2. The micro-fibre material may be either of a suitable fibre forming composition of mineral, metals, polymers, or any other element capable of being formed into micro-fibres. A suitable polymeric composition is preferably polypropylene, although it is appreciated tiiat there are several other types of polymeric material which may be spun to form the micro-fibres of the layered product. Examples of such additional polymeric materials include poly aery lates, polyamides, polyesters and polystyrenes. The process for forming such micro-fibres are as described in the aforementioned applicant's issued Canadian Patent 1,057,924. The process by which those fibres are formed into a suitable layer is described in Canadian Patents 1,278,659 and 1,311,889. The alternative embodiments for the filter element, as described witii respect to Figure 2 and Figure 8 have somewhat different efficiencies. It has been found tiiat a single layer of die micro-fibre material 76 of Figure 2 is not as efficient as the multiple layers of micro-fibre material 118, of Figure 8. By virtue of layering the micro-fibre sheet material, the filtering action is substantially enhanced for a given radial tiiickness to remove for a specific radial tiiickness substantially all of the particulate material thereby only leaving the gaseous components to be removed by die outer filter 116. The second filter component which surrounds die first filter component is preferably made of activated carbon to adsorb die gaseous components not trapped by die inner filter element 114. It is appreciated tiiat the outer filter element 116 may however be made of other types of material for adsorbing gaseous components such as zeolite materials sold by Union Carbide under the trade mark Silicalite and as previously used in cigarette filters such as in U.S. Patent No. 3,327,718. When powdered Silicalites, activated carbon and die like is used die outer filter 116 may be formed by holding the powdered material around die inner filter by a porous mesh of Figure 2 A or the like. Although the mesh is porous to air flow, it is impervious to the powdered material to retain thereby die powdered material in the desired shape. The preferred outer filter material is made of activated carbon fibre which is provided in sheet form. The outer filter element 116 may be made in the form a single sheet of a desired tiiickness or alternatively, the sheets 122 may be layered onto itself as shown in Figure 8 to develop die desired tiiickness for the outer filter element 116. The activated carbon fibres for the sheets 122 may be obtained from various sources of supply, for example, from Futamura Chemical Industries of Nagoya, Japan. The cigarette tube 106 has its innermost end 108 secured between the outer filter element 116 and the inner filter element 114. The layers 118 are compressed to some extent in region 124 such that tiiey can be positioned witiiin die inside of die inner end 108 of die tube 106. The outer filter element 116 is then positioned on die outside 126 of die cigarette tube 106. Preferably, adhesive is used to adhere end 108 to die inner filter element in region 124 and die outer filter element in region 128. The cigarette tube 106 is preferably formed of layers of sheet material 112. The layered tube 106 has sufficient structural rigidity such tiiat when the open end 110 is secured to die cigarette holder 36 of Figure 1 the tube is suspended witiiin the housing of the smoker's accessory. It is appreciated tiiat the layers for the cigarette tube 106 may be formed of a variety of materials. It is also appreciated tiiat the cigarette tube may be made from a single layer of material which may have a thickness equivalent to the thickness of the multiple layers 112 for die cigarette tube. The preferred material for the cigarette tube 106 is a plurality of overlaid sheets of carbon filled paper. The carbon filled paper may or may not contain a fire retardant to inhibit ignition of the carbon paper by die glowing cigarette. There are several suppliers of carbon paper which may or may not include a fire retardant. The carbon paper typically has a thickness in the range of 0.1 to 2 mm and is non-porous to die cigarette sidestream smoke. That is, when the cigarette is burning within the cigarette tube smoke cannot escape through the cigarette tube so that all sidestream smoke as emitted by die burning cigarette must pass dirough die filter element 98. It is appreciated tiiat such carbon paper may be porous to air unlike the alternate structures such as tiie glass tube. In accordance witii a preferred embodiment of die invention, it has been found tiiat a marginal porosity to air for the cigarette tube is beneficial. That is, the tobe material is porous to air under high pressure which equates to a high pressure drop across die material, but continues to be non-porous to die cigarette smoke particulate components and gaseous components. Although the success in a slight porosity for the cigarette tube is not completely understood, it is tiiought that the hot gases developed witiiin die tube can escape to some extent while leaving the cigarette smoke components within the tube to be drawn away by die fan. The degree of porosity for the tube relative to the filter element is slight; for example, in Corseta units, the carbon paper cigarette tube has a porosity in the range of about 20 to about 50 Corseta units whereas die filter element has a porosity in the range of about 10,000 Corseta units. We have also determined that the cigarette tube ranges in diameter from about 1.5 times the diameter of the cigarette and greater. It has been found tiiat for cigarette tubes having diameters less than about 1.5 times the diameter of die cigarette, the tube material is hence to close to the lit cigarette and charring or overheating of die cigarette occurs which leads to unsatisfactory smoke taste. In view of the tube cross-section being of a variety of shapes it is understood tiiat diameter for die tube is intended to cover die average width dimension of the tube interior. A cap 100 is provided to close die end 99 for the filter element 98. The cap 100 has an annular ridge 130 which is positioned between the inner filter element 114 and die outer filter 116. The annular portion 130 may be secured between the inner and outer filter elements by a suitable adhesive. Preferably die outer filter element 116 extends beyond die inner element 114, the thickness of the cap 100 so as to provide a flush end for die sidestream filter cartridge. Figure 9 shows an alternative embodiment for the exhale filter 24. The exhale filter has an inner filter element 132 and an outer filter element 134. The exhale filter element 24 has its distal end closed by a dap 136 which may fit between the inner and outer filter elements and be shaped as per the cap 100 of Figure 8. The cap 136 may be glued in position where the outer filter element 134 extends beyond me inner filter element 132, me thickness of die cap to provide a flush end for the filter element 24. The inner filter element 132 may be formed of the same micro-fibre material used in me inner filter element of Figure 8. Similarly, the outer filter material 134 may be formed from a sheet of activated carbon fibre used in the outer filter element 116 of Figure 8. Also, the several alternatives for the inner and outer filter materials, described witii respect to Figure 8 may also be used in die exhale filter of Figure 9. The inner tubular filter 132 has an inlet end 138 which extends beyond die end portion 140 of the outer filter. This inlet end portion 138 is shown in more detail in Figure 10. The layers 142 of the inner filter 132 may be adhered together or may be encased in an outer ring 144 to give that projecting portion 138 sufficient structural integrity such that it may be inserted in a suitable mouth piece such as mouth piece 62 of Figure 1. As shown in Figure 10, die inner layers 142 of the micro-fibre material are considerably thinner than the outer layers of d e activated carbon fibre material. The size and packing weight of the inner filter material for the embodiments of Figures 7 and 9 may be in the same range as with the inner filter material of Figure 2; that is, a total thickness in the range of about 0.3 mm to about 6 mm and a packing weight in the range of about 5 g/m 2 to about 500 g/m 2 based on die total thickness. The individual sheets of material may have a thickness in the range of about 0.1 mm to about 3 mm. The preferred ranges for the packing weight is in the range of about 10 to about 200 g/m 2 for sheet thickness of about 0.15 to about 3 mm and die especially preferred range of packing densities in the range of about 10 g/m 2 to about 50 g/m 2 for sheet thickness of about 0.15 to about 0.3 mm. The micro-fibre material as used in die inner filter is especially useful in removing cigarette smoke particles as small as about 0.2 microns in size. The preferred size for the micro-fibres in the inner filter is in the range of about 0.5 to about 2.5 microns. The sufficient radial tiiickness of the carbon fibre filter is normally in the range of about 1 mm to about 7 mm. The micro-fibre material of tiie filter elements of the various embodiments of the invention are particularly efficient in the removal of particulates having sizes in die range of about 0.2 microns and greater. It is appreciated tiiat in varying the thickness of the fibre the entire range of smoke particulates can be removed even including tiiose having sizes less than about 0.3 microns. Although tiie principle of filtration by the micro- fibres is not very well understood, it is tiiought that the diameter of the particles of the cigarette smoke are in the range of about 0.1 to about 0.6 microns. The small diameter micro-fibres used in the filter avoid displacement in d e direction of travel of the particles such that they collide directly with die micro-fibres and are tiien held by die micro-fibres. This is in contrast to the normal ti icker fibres typically employed in conventional cellulose acetate filters. Those fibre sizes are normally in range of about 10 to about 25 microns which causes a displacement in die air flow around the fibre so that the particles are diverted from colliding directing witii the fibres. This has been demonstrated by testing on several occasions where filter material of the significantly thicker diameter fibres is far less effective in removing the smaller particulates than die micro-fibre material having diameter sizes in the range of about 0.1 to about 10 microns and preferably less tiian about 5 microns. In some applications the preferred fibre size may range from about 0.5 to about 2.5 microns. A further alternative for the filter embodiments of Figures 7 and 9 is spacing the outer tubular filter element 116, for example, of activated carbon from the inner filter element 114. The ends of die filter element 98 would be appropriately sealed to direct all gaseous components through such annular space and into the outer filter. Such annular space may be filled with suitable oxidizing catalysts to degrade die smoke gaseous components before passing through the outer carbon filter. The alternative of a course filter element, inside die micro-filter element as described witii respect to Figure 2 may be used as well witii the layered micro-fibre 114. Such coarse filter element may be of standard cellulose acetate fibres having diameters in the range of about 20 μm. The coarse filter element removes the coarse smoke particles of cigarette ash and die like in advance of die micro-fibre filter. It is, of coarse, appreciated tiiat the cigarette ash which remain within the filter element may be dumped out of the sidestream filter element, or retained in the sidestream filter element until time for replacement. It has been found tiiat leaving cigarette ash in die filter element does not detract from filter efficiency when either the coarse fibre or micro-fibre filter elements are innermost of the inner elongate chamber. The sidestream and exhale filter cartridges in accordance witii tiiis invention may be employed in various types of smoker's accessories which have provision for drawing me sidestream smoke through the filter element by allowing fresh air to enter die inlet end of die cigarette tobe. Similarly, the exhale filter cartridge may be used witii the smoker's accessory which filters sidestream smoke or may be used independently of tiiat other accessory. The exhale filter may be individually hand held and brought to die moutii whenever exhale of cigarette smoke is desired. The exhale filter cartridge is as shown in Figure 9 compared to Figure 7 is considerably larger to provide die least amount of pressure drop so tiiat one may exhale into the filter in an almost normal manner as though they were exhaling into the surroundings. Preferably the low pressure drop for die exhale filter is in the range of about 0.5 mm to about 10 mm of H 2 0. In view of the filter cartridges being replaceable in a smoker's accessory or the like, it is understood tiiat the filter cartridges may be sold separately of the smoker's accessory. The cartridges may be sold in packages of 5 or 10 and may be sold in conjunction with the cigarettes. Preferably the filter cartridges are capable of filtering cigarette smoke from up to about 20 to 25 about cigarettes, hence only requiring replacement of the filter cartridges witii every pack of cigarettes smoked. Although preferred embodiments of die invention are described herein in detail, it will be understood by tiiose skilled in die art that variations may be made tiiereto without departing from the spirit of the invention or the scope of die appended claims.

Claims: CLAIMS: 1. A cigarette smoke filter for use in a smoker's accessory for filtering cigarette smoke, said filter comprising: a tubular filter consisting of micro-fibres for removing particulate material from cigarette smoke, said tubular filter having an inlet end for cigarette smoke to enter an inner elongate chamber within said tubular filter, said tobular filter having a closed end opposite said inlet end, said micro- fibres having an average tiiickness in the range of about 0.5 to about 10 microns and made from a suitable fibre forming composition, said tobular filter being of sufficient tiiickness to remove substantially all particulate components from cigarette smoke passing from said inner elongate chamber dirough said tabular filter, said micro-fibre filter material having a low pressure drop to permit an air stream to flow through said filter with minimal resistance to such flow. 2. A cigarette smoke filter of claim 1 wherein said filter has multiple layers of different filtering material, an innermost tubular filter being provided inside said tobular filter of micro-fibre, said innermost filter comprising a coarse filter material for removing larger smoke particulate components. 3. A cigarette smoke filter of claim 1 wherein said filter has multiple layers of different filtering material; an outer filter shell surrounding said tobular filter, said outer filter shell consisting of activated carbon material held by a support matrix which is porous to air flow, said tubular filter of micro-fibre being an inner filter relative to said outer filter, said activated carbon outer filter shell being of sufficient radial tiiickness for adsorbing substantially all gaseous components of cigarette smoke from such filtered cigarette smoke stream, said inner tobular filter in combination with activated carbon outer filter providing a filtered air stream substantially free of cigarette smoke for discharge into surroundings. 4. A cigarette smoke filter of claim 3 wherein an innermost tubular filter is provided inside said inner tobular filter, said innermost filter comprising a coarse filter material for removing larger smoke particulate components. 5. A cigarette smoke filter of claim 4 wherein said inner tobular filter comprises several individual layers of micro-fibre material. 6. A cigarette smoke filter of claim 5 wherein said several layers are of a thin sheet of micro-fibres formed from a polymeric material, said sheet having a widtii which defines a length dimension of said tobular filter, said layers of polymeric sheet material providing a stage-wise removal of particulates from cigarette smoke to enhance thereby filter performance. 7. A cigarette smoke filter of claim 3 wherein said activated carbon material is in the form of activated carbon particles held by a mesh support, said particles of activated carbon being held in place about said inner tobular filter by said mesh support. 8. A cigarette smoke filter of claim 3 wherein said activated carbon is in the form of an integral matt of activated carbon fibres. 9. A cigarette smoke filter of claim 8 wherein said matt of carbon fibres is thinner than said sufficient tiiickness of said activated carbon filter, said matt being wrapped around onto itself to form several layers of said sufficient radial tiiickness. 10. A cigarette smoke filter of claim 1 wherein said micro-fibres are of polypropylene, said sufficient radial tiiickness for said inner filter being in the range of about 0,3 mm to about 6 mm and a packing weight in the range of about 5 g/m 2 to about 500 g/m 2 for a sheet thickness in the range of about 0.1 mm to about 3 mm. 11. A cigarette smoke filter of claim 10 wherein said packing weight is in the range of about 10 g/m 2 to about 200 g/m 2 . 12. A cigarette smoke filter of claim 11 wherein said packing weight is in the range of about 10 g/m 2 to about 50 g/m 2 . 13. A cigarette smoke filter of claim 1 wherein said inner tobular filter having micro-fibres of a diameter of less than about 5 microns removes smoke particles of about 0.2 microns in thickness and greater from cigarette smoke. 14. A cigarette smoke filter of claim 13 wherein said micro-fibres have a diameter in die range of about 0.5 to about 2.5 microns. 15. A cigarette smoke filter of claim 9 wherein said sufficient radical tiiickness is in the range of about 1 mm to about 7 mm. 16. A cigarette smoke filter cartridge for use in a smoker's accessory for filtering sidestream smoke emitted from a burning cigarette, said cartridge comprising: a cigarette tobe in which a burning cigarette is placed, said cigarette tube being at least as long as a cigarette to be smoked and having a diameter at least 1.5 times the diameter of a cigarette, said cigarette tobe being non- porous to sidestream cigarette smoke, a porous low pressure drop tobular filter element at an end of said cigarette tobe for removing sidestream smoke, said filter element having an inlet end for sidestream cigarette smoke to enter an inner elongate chamber within said tubular filter, said tobular filter having a closed end opposite said inlet end, means for connecting a first end of said cigarette tobe to said inlet end of said filter element whereby sidestream smoke to be filtered flows along said cigarette tube, into said inner chamber, and radially outwardly dirough said tobular filter element, and a second end of said cigarette tobe being open to permit insertion of a lit cigarette into said cigarette tobe, said second end of said cigarette tobe being adapted to be received by a holder for a lit cigarette. 17. A cigarette smoke filter cartridge of claim 16 wherein said cigarette tobe is a non-flammable paper impregnated witii activated carbon material. 18. A cigarette smoke filter cartridge of claim 17 wherein said paper is thinner than a desired thickness for tobe wall, several layers of said paper being layered to make up said desired tobe wall thickness. 19. A cigarette smoke filter cartridge of claim 16 wherein said tubular filter element comprises: an inner tobular filter consisting of micro-fibres for removing particulate material from sidestream cigarette smoke, said inner tobular filter having said inlet end, said closed end and said inner elongate chamber, said micro-fibres having an average tiiickness in the range of about 0.5 to about 10 microns and being made from a suitable micro-fibre forming composition, an outer filter shell surrounding said inner tobular filter, said outer filter shell consisting of activated carbon material held by a support matrix which is porous to air flow, said inner tobular filter being of sufficient thickness to remove substantially all particulate material from cigarette smoke passing radially from said inner elongate chamber through said tobular filter, said micro- fibre filter material having a low pressure drop to permit an air stream to flow through said filter with minimal resistance to such flow, said activated carbon outer filter shell being of sufficient thickness for adsorbing substantially all remaining traces of cigarette smoke from such filtered sidestream cigarette smoke, said inner tobular filter in combination with activated charcoal outer filter providing a filtered air stream substantially free of cigarette smoke for discharge into surroundings. 20. A cigarette smoke filter cartridge of claim 19 wherein said inner tobular filter comprises: several overlaid layers of a tiiin sheet of micro-fibre forming polymeric material, said sheet having a widtii which defines a lengtii dimension of said tubular filter. 21. A cigarette smoke filter cartridge of claim 19 wherein said activated carbon material is in the form of activated carbon particles held by a mesh support, said particles of activated carbon being held in place surrounding said inner tobular filter by said mesh support. 22. A cigarette smoke filter cartridge of claim 19 wherein said activated carbon is in the form of a mat of activated carbon fibres. 23. A cigarette smoke filter cartridge of claim 17 wherein said matt of carbon fibres is tiiinner than said sufficient radical thickness of said activated carbon filter, said matt is wrapped onto itself to form several layers of said sufficient radial tiiickness. 24. A cigarette smoke filter cartridge of claim 19 wherein said micro- fibres are of polypropylene, said sufficient radical tiiickness for said inner filter being in the range of about 0.03 mm to about 6 mm and a packing weight in the range of about 5 g/m 2 to about 500 g/m 2 for a sheet thickness in the range of about 0.1 mm to about 3 mm. 25. A cigarette smoke filter cartridge of claim 24 wherein said packing weight is in the range of about 10 g/m 2 to about 200 g/m 2 . 26. A cigarette smoke filter cartridge of claim 25 wherein said packing weight is in the range of about 10 g/m 2 to about 50 g/m 2 . 27. A cigarette smoke filter cartridge of claim 19 wherein said inner tobular filter having micro-fibres of a diameter of less than about 5 microns removes smoke particles of about 0.2 microns in the thickness and greater from cigarette smoke. 28. A cigarette smoke filter of cartridge claim 27 wherein said micro- fibres have a diameter in die range of about 0.5 to about 2.5 microns. 29. A cigarette smoke filter cartridge of claim 23 wherein said sufficient radical tiiickness is in the range of about 1 mm to about 7 mm. 30. A cigarette smoke filter cartridge for use in filtering cigarette smoke exhaled by a cigarette smoker, said cartridge comprising: an inner tubular filter consisting of micro-fibres for removing particulate material from cigarette smoke, said tobular filter having an inlet end for cigarette smoke to enter an inner elongate chamber within said tobular filter, said tobular filter having a closed end opposite said inlet end, said micro-fibres having an average diameter in the range of about 0.5 to about 10 microns and being made from a suitable micro-fibre forming composition, an outer filter shell surrounding said inner filter, said outer filter shell consisting of activated carbon material held by a support matrix which is porous to air flow, said inner tobular filter being of sufficient tiiickness to remove substantially all particulate material from cigarette smoke passing radially from said inner elongate chamber through said tobular filter, said micro- fibre filter material having a low pressure drop to permit an air stream to flow through said filter with minimal resistance to such flow, said activated carbon outer filter shell being of sufficient tiiickness for adsorbing substantially all gaseous components of cigarette smoke from such filtered exhaled cigarette smoke stream, said cartridge having an end portion adjacent said inlet end, said end portion being received by an exhale mouthpiece to facilitate a user exhaling into said filter cartridge, and said inner tobular filter in combination with activated carbon outer filter providing a filtered air stream substantially free of cigarette smoke for discharge into surroundings. 31. A cigarette smoke filter cartridge of claim 30 wherein said end portion is an extension of said inner tobular filter beyond said outer filter shell to provide a tubular shaped end portion and means for strengthening said end portion to facilitate receipt by an exhale moumpiece. 32. A cigarette smoke filter cartridge of claim 30 wherein said inner tubular filter comprises: several overlaid layers of a thin sheet of micro-fibre forming polymeric material, said sheet having a widtii which defines a lengtii dimension of said tobular filter. 33. A cigarette smoke filter cartridge of claim 30 wherein said activated carbon material is in die form of activated carbon particles held by a mesh support, said particles of activated carbon being held in place surrounding said inner tobular filter. 34. A cigarette smoke filter cartridge of claim 30 wherein said activated carbon is in the form of a mat of activated carbon fibres. 35. A cigarette smoke filter cartridge of claim 34 wherein said matt of carbon fibres is thinner tiian said sufficient radial tiiickness of said activated carbon filter, said matt is wrapped onto itself to form several layers of said sufficient radial thickness. 36. A cigarette smoke filter cartridge of claim 30 wherein said micro- fibres are of fibre forming polypropylene, said sufficient radial thickness for said inner filter being in the range of about 0.03 mm to about 6 mm and a packing weight in the range of about 5 g/m 2 to about 500 g/m 2 for a sheet thickness in the range of about 0.1 mm to about 3 mm. 37. A cigarette smoke filter cartridge of claim 36 wherein said packing weight is in die range of about 10 g/m 2 to about 200 g/m 2 . 38. A cigarette smoke filter cartridge of claim 37 wherein said packing weight is in die range of about 10 g/m 2 to about 50 g/m 2 . 39. A cigarette smoke filter cartridge of claim 38 wherein said inner tobular filter having micro-fibres of a diameter of less than about 5 microns removes smoke particles of about 0.2 microns in the thickness and greater from cigarette smoke. 40. A cigarette smoke filter cartridge of claim 39 wherein said micro- fibres have a thickness in the range of about 0.5 to about 2.5 microns. 41. A cigarette smoke filter cartridge of claim 30 wherein said sufficient radial tiiickness is in the range of about 1 mm to about 7 mm. 42. A cigarette smoke filter cartridge of claim 30 housed in a housing, said housing having a mouthpiece with said cartridge end portion fitted in said moutiipiece, said housing having an outiet through which a filtered air stream substantially free of cigarette smoke travels when a user exhales cigarette smoke through said moutiipiece into said filter cartridge.

Inventors: BOWEN LARRY, SNAIDR STANISLAV M, BOWEN, LARRY, SNAIDR, STANISLAV, M.
Applicants: ROTHMANS BENSON & HEDGES, ROTHMANS, BENSON & HEDGES INC.
Application year: 1994
Main classification: A24F13
IPC codes: A24D3, A24F13